1. Field of the Invention
This invention relates to cutting tools, and more particularly concerns pruning shears mounted upon an elongated handle and equipped with an actuating tether deployed along said handle.
2. Description of the Prior Art
Conventional tree and shrub pruners are typically comprised of cutting shears mounted atop a pole of fixed or telescopically adjustable length with an actuating rope or cable extending from said shears to the lowermost extremity of the pole. The shears are generally comprised of a stationary member having a hook configuration disposed in the same plane as the pole, and a cutting blade interactive with the stationary member to sever a limb engaged by said stationary member. The pruning shears are manipulated by holding the pole in one hand and the rope in the other hand in order to pull the rope and thereby force the blade against an engaged limb. The blade is returned to a stand-by starting position by virtue of a restoring spring.
Representative examples of such pruning devices are described in U.S. Pat. Nos. 4,033,036; 4,096,630; 5,084,975; 5,613,301; 5,743,018; 5,996,232 and elsewhere.
Manipulation of the pruning device and actuation of the cutting blade can be difficult, depending upon the height of the limb to be severed, its orientation and location, and the presence of closely adjacent interfering structures. In particular, it is difficult to cut branches which have a nearly vertical orientation because the stationary hook member must engage the branch in such manner that the branch is transversely oriented relative to the pole. Ideally, the branch to be severed is disposed in orthogonal relationship to the pole.
When the pruning device is operated at ground level, the operator can walk around the base of the tree to find the best angle of application of the device for the cutting of a particular branch. However, when the operator is on a rooftop or in some other situation which restricts movement relative to the branch to be severed, considerable difficulty is encountered.
U.S. Pat. No. 4,033,036 to Morris discloses a pole type pruning device wherein the cutting head can be adjustably pivoted to positions wherein the plane of the hook member is disposed between 0 and 90 degrees relative to the pole axis. However, in achieving such adjustability, the upper structure of his pruning device has been weakened, and the force required to effectively pull the rope has been significantly increased.
It is accordingly an object of the present invention to provide a pole type pruning device having a tether-actuated cutting head which is angularly adjustable relative to an elongated supporting pole.
It is another object of this invention to provide an adjustable pruning device as in the foregoing object wherein achievement of adjustability does not adversely affect the strength of the pruning device.
It is a further object of the present invention to provide an adjustable pruning device of the aforesaid nature wherein achievement of adjustability does not significantly increase the amount of pulling force needed to be applied to said rope to actuate said cutting head.
It is yet another object of this invention to provide a pruning device of the aforesaid nature of durable, simple construction amenable to low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.
The above and other beneficial objects and advantages are accomplished in accordance with the present invention by a pruning device for cutting tree limbs comprising:
1) a support pole elongated upon a straight axis between upper and lower extremities,
2) a pruner assembly associated with the upper extremity of said pole and comprised of:
a) an engaging member having a base portion and an upper portion having a hook shaped configuration defining a downwardly directed gripping region adapted to rest upon a limb intended to be severed, and
b) a cutting member having a lower blade portion and upper lever arm portion, said cutting member being pivotally joined to said engaging member at a site between said blade and lever arm portions,
3) tether means secured to said lever arm portion and having sufficient length to extend to a free terminal extremity below the lower extremity of said support pole, whereby pulling motion applied to said tether produces forceful traversal of said blade portion through said gripping region,
4) restoring spring means interactive between said engaging member and lever arm portion and biased against the force applied by said pulling motion, and
5) a pivot mechanism interactive between the base portion of said engaging member and the upper extremity of said pole, said pivot mechanism comprising:
a) a knuckle joint comprised of slideably interactive upper and lower members secured by a threaded tightening bolt upon which rotative motion of said upper member is centered,
b) a rotating control wheel positioned at a site below said bolt and centered at 45 degrees of angular displacement from said axis, said wheel having a diameter such as to tangentially receive said tether in a straight vertical path, and
c) an upper guide mounted above said control wheel, and a lower guide positioned below said control wheel, said guides permitting sliding motion of said tether in its direction of elongation but preventing lateral displacement thereof, whereby,
6) said rotative movement of said upper joint member and attached pruner assembly enables said engaging member to be securably positioned at various angles of between 0 and 90 degrees relative to the pole axis in a path parallel to but displaced from said pole axis, and the pulling functionality of said tether remains effective at all positions of said pruner assembly.